This invention relates to supporting glass sheets and specifically refers to an improved method of employing self-closing metal tongs that grip glass sheets during thermal treatment. Tongs have been used for supporting glass sheets in vertical planes for thermal treatment by gripping the opposite glass sheet surfaces near their upper edges. The tongs are supported on an overhead monorail which extends through thermal treatment apparatus by means of a supporting clevis mounted to a carriage that rides on the monorail.
Glass sheets are heated to substantially the softening point before being pressed to shape, cooled for tempering or annealing, or coated. Tongs for gripping glass sheets are provided with tong points or discs that penetrate the glass sheet surfaces and mar the latter and cause dents and scratches in the vicinity of the gripping areas and even deposit oxides of the glass engaging members in the surface of the glass during the temperature cycle. The glass sheet so treated is weakened in the vicinity of the locations where the glass engaging elements of the tongs engage the glass sheet. Hence, a long felt need existed in the glass handling art to provide tongs that do not weaken the glass appreciably in the vicinity of the glass areas that are gripped by the glass engaging elements of the tongs.